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Rampogu S, Baek A, Gajula RG, Zeb A, Bavi RS, Kumar R, Kim Y, Kwon YJ, Lee KW. Ginger (Zingiber officinale) phytochemicals-gingerenone-A and shogaol inhibit SaHPPK: molecular docking, molecular dynamics simulations and in vitro approaches. Ann Clin Microbiol Antimicrob 2018; 17:16. [PMID: 29609660 PMCID: PMC5879566 DOI: 10.1186/s12941-018-0266-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 03/09/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Antibiotic resistance is a defense mechanism, harbored by pathogens to survive under unfavorable conditions. Among several antibiotic resistant microbial consortium, Staphylococcus aureus is one of the most havoc microorganisms. Staphylococcus aureus encodes a unique enzyme 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (SaHPPK), against which, none of existing antibiotics have been reported. METHODS Computational approaches have been instrumental in designing and discovering new drugs for several diseases. The present study highlights the impact of ginger phytochemicals on Staphylococcus aureus SaHPPK. Herein, we have retrieved eight ginger phytochemicals from published literature and investigated their inhibitory interactions with SaHPPK. To authenticate our work, the investigation proceeds considering the known antibiotics alongside the phytochemicals. Molecular docking was performed employing GOLD and CDOCKER. The compounds with the highest dock score from both the docking programmes were tested for their inhibitory capability in vitro. The binding conformations that were seated within the binding pocket showing strong interactions with the active sites residues rendered by highest dock score were forwarded towards the molecular dynamic (MD) simulation analysis. RESULTS Based on molecular dock scores, molecular interaction with catalytic active residues and MD simulations studies, two ginger phytochemicals, gingerenone-A and shogaol have been proposed as candidate inhibitors against Staphylococcus aureus. They have demonstrated higher dock scores than the known antibiotics and have represented interactions with the key residues within the active site. Furthermore, these compounds have rendered considerable inhibitory activity when tested in vitro. Additionally, their superiority was corroborated by stable MD results conducted for 100 ns employing GROMACS package. CONCLUSIONS Finally, we suggest that gingerenone-A and shogaol may either be potential SaHPPK inhibitors or can be used as fundamental platforms for novel SaHPPK inhibitor development.
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Affiliation(s)
- Shailima Rampogu
- Division of Applied Life Science (BK21 Plus Program), Systems and Synthetic Agrobiotech Center (SSAC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Natural Science (RINS), Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Ayoung Baek
- Division of Applied Life Science (BK21 Plus Program), Systems and Synthetic Agrobiotech Center (SSAC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Natural Science (RINS), Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Rajesh Goud Gajula
- Primer Biotech Research Center, Jaipuri Colony, Nagole, Hyderabad, Telangana, 500068, India
| | - Amir Zeb
- Division of Applied Life Science (BK21 Plus Program), Systems and Synthetic Agrobiotech Center (SSAC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Natural Science (RINS), Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Rohit S Bavi
- Division of Applied Life Science (BK21 Plus Program), Systems and Synthetic Agrobiotech Center (SSAC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Natural Science (RINS), Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Raj Kumar
- Division of Applied Life Science (BK21 Plus Program), Systems and Synthetic Agrobiotech Center (SSAC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Natural Science (RINS), Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Yongseong Kim
- Department of Science Education, Kyungnam University, Changwon, 51767, Republic of Korea
| | - Yong Jung Kwon
- Department of Chemical Engineering, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Keun Woo Lee
- Division of Applied Life Science (BK21 Plus Program), Systems and Synthetic Agrobiotech Center (SSAC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Research Institute of Natural Science (RINS), Gyeongsang National University, Jinju, 52828, Republic of Korea.
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Dennis ML, Pitcher NP, Lee MD, DeBono AJ, Wang ZC, Harjani JR, Rahmani R, Cleary B, Peat TS, Baell JB, Swarbrick JD. Structural Basis for the Selective Binding of Inhibitors to 6-Hydroxymethyl-7,8-dihydropterin Pyrophosphokinase from Staphylococcus aureus and Escherichia coli. J Med Chem 2016; 59:5248-63. [PMID: 27094768 DOI: 10.1021/acs.jmedchem.6b00002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) is a member of the folate biosynthesis pathway found in prokaryotes and lower eukaryotes that catalyzes the pyrophosphoryl transfer from the ATP cofactor to a 6-hydroxymethyl-7,8-dihydropterin substrate. We report the chemical synthesis of a series of S-functionalized 8-mercaptoguanine (8MG) analogues as substrate site inhibitors of HPPK and quantify binding against the E. coli and S. aureus enzymes (EcHPPK and SaHPPK). The results demonstrate that analogues incorporating acetophenone-based substituents have comparable affinities for both enzymes. Preferential binding of benzyl-substituted 8MG derivatives to SaHPPK was reconciled when a cryptic pocket unique to SaHPPK was revealed by X-ray crystallography. Differential chemical shift perturbation analysis confirmed this to be a common mode of binding for this series to SaHPPK. One compound (41) displayed binding affinities of 120 nM and 1.76 μM for SaHPPK and EcHPPK, respectively, and represents a lead for the development of more potent and selective inhibitors of SaHPPK.
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Affiliation(s)
- Matthew L Dennis
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia.,CSIRO Biosciences Program , Parkville, Victoria 3052, Australia
| | - Noel P Pitcher
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Michael D Lee
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Aaron J DeBono
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Zhong-Chang Wang
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia.,State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University , Nanjing 210093, People's Republic of China
| | - Jitendra R Harjani
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Raphaël Rahmani
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Ben Cleary
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - Thomas S Peat
- CSIRO Biosciences Program , Parkville, Victoria 3052, Australia
| | - Jonathan B Baell
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | - James D Swarbrick
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
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Dennis ML, Chhabra S, Wang ZC, Debono A, Dolezal O, Newman J, Pitcher NP, Rahmani R, Cleary B, Barlow N, Hattarki M, Graham B, Peat TS, Baell JB, Swarbrick JD. Structure-based design and development of functionalized Mercaptoguanine derivatives as inhibitors of the folate biosynthesis pathway enzyme 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase from Staphylococcus aureus. J Med Chem 2014; 57:9612-26. [PMID: 25357262 DOI: 10.1021/jm501417f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK), an enzyme from the folate biosynthesis pathway, catalyzes the pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin and is a yet-to-be-drugged antimicrobial target. Building on our previous discovery that 8-mercaptoguanine (8MG) is an inhibitor of Staphylococcus aureus HPPK (SaHPPK), we have identified and characterized the binding of an S8-functionalized derivative (3). X-ray structures of both the SaHPPK/3/cofactor analogue ternary and the SaHPPK/cofactor analogue binary complexes have provided insight into cofactor recognition and key residues that move over 30 Å upon binding of 3, whereas NMR measurements reveal a partially plastic ternary complex active site. Synthesis and binding analysis of a set of analogues of 3 have identified an advanced new lead compound (11) displaying >20-fold higher affinity for SaHPPK than 8MG. A number of these exhibited low micromolar affinity for dihydropteroate synthase (DHPS), the adjacent, downstream enzyme to HPPK, and may thus represent promising new leads to bienzyme inhibitors.
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Affiliation(s)
- Matthew L Dennis
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
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Chhabra S, Barlow N, Dolezal O, Hattarki MK, Newman J, Peat TS, Graham B, Swarbrick JD. Exploring the chemical space around 8-mercaptoguanine as a route to new inhibitors of the folate biosynthesis enzyme HPPK. PLoS One 2013; 8:e59535. [PMID: 23565155 PMCID: PMC3614987 DOI: 10.1371/journal.pone.0059535] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Accepted: 02/15/2013] [Indexed: 11/18/2022] Open
Abstract
As the second essential enzyme of the folate biosynthetic pathway, the potential antimicrobial target, HPPK (6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase), catalyzes the Mg(2+-)dependant transfer of pyrophosphate from the cofactor (ATP) to the substrate, 6-hydroxymethyl-7,8-dihydropterin. Recently, we showed that 8-mercaptoguanine (8-MG) bound at the substrate site (KD ∼13 µM), inhibited the S. aureus enzyme (SaHPPK) (IC50 ∼ 41 µM), and determined the structure of the SaHPPK/8-MG complex. Here we present the synthesis of a series of guanine derivatives, together with their HPPK binding affinities, as determined by SPR and ITC analysis. The binding mode of the most potent was investigated using 2D NMR spectroscopy and X-ray crystallography. The results indicate, firstly, that the SH group of 8-MG makes a significant contribution to the free energy of binding. Secondly, direct N(9) substitution, or tautomerization arising from N(7) substitution in some cases, leads to a dramatic reduction in affinity due to loss of a critical N(9)-H···Val46 hydrogen bond, combined with the limited space available around the N(9) position. The water-filled pocket under the N(7) position is significantly more tolerant of substitution, with a hydroxyl ethyl 8-MG derivative attached to N(7) (compound 21a) exhibiting an affinity for the apo enzyme comparable to the parent compound (KD ∼ 12 µM). In contrast to 8-MG, however, 21a displays competitive binding with the ATP cofactor, as judged by NMR and SPR analysis. The 1.85 Å X-ray structure of the SaHPPK/21a complex confirms that extension from the N(7) position towards the Mg(2+)-binding site, which affords the only tractable route out from the pterin-binding pocket. Promising strategies for the creation of more potent binders might therefore include the introduction of groups capable of interacting with the Mg(2+) centres or Mg(2+)-binding residues, as well as the development of bitopic inhibitors featuring 8-MG linked to a moiety targeting the ATP cofactor binding site.
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Affiliation(s)
- Sandeep Chhabra
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- CSIRO Division of Materials, Science and Engineering, Parkville, Australia
| | - Nicholas Barlow
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Olan Dolezal
- CSIRO Division of Materials, Science and Engineering, Parkville, Australia
| | - Meghan K. Hattarki
- CSIRO Division of Materials, Science and Engineering, Parkville, Australia
| | - Janet Newman
- CSIRO Division of Materials, Science and Engineering, Parkville, Australia
| | - Thomas S. Peat
- CSIRO Division of Materials, Science and Engineering, Parkville, Australia
| | - Bim Graham
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - James D. Swarbrick
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- * E-mail:
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Chhabra S, Dolezal O, Collins BM, Newman J, Simpson JS, Macreadie IG, Fernley R, Peat TS, Swarbrick JD. Structure of S. aureus HPPK and the discovery of a new substrate site inhibitor. PLoS One 2012; 7:e29444. [PMID: 22276115 PMCID: PMC3261883 DOI: 10.1371/journal.pone.0029444] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 11/28/2011] [Indexed: 12/17/2022] Open
Abstract
The first structural and biophysical data on the folate biosynthesis pathway enzyme and drug target, 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (SaHPPK), from the pathogen Staphylococcus aureus is presented. HPPK is the second essential enzyme in the pathway catalysing the pyrophosphoryl transfer from cofactor (ATP) to the substrate (6-hydroxymethyl-7,8-dihydropterin, HMDP). In-silico screening identified 8-mercaptoguanine which was shown to bind with an equilibrium dissociation constant, Kd, of ∼13 µM as measured by isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR). An IC50 of ∼41 µM was determined by means of a luminescent kinase assay. In contrast to the biological substrate, the inhibitor has no requirement for magnesium or the ATP cofactor for competitive binding to the substrate site. The 1.65 Å resolution crystal structure of the inhibited complex showed that it binds in the pterin site and shares many of the key intermolecular interactions of the substrate. Chemical shift and 15N heteronuclear NMR measurements reveal that the fast motion of the pterin-binding loop (L2) is partially dampened in the SaHPPK/HMDP/α,β-methylene adenosine 5′-triphosphate (AMPCPP) ternary complex, but the ATP loop (L3) remains mobile on the µs-ms timescale. In contrast, for the SaHPPK/8-mercaptoguanine/AMPCPP ternary complex, the loop L2 becomes rigid on the fast timescale and the L3 loop also becomes more ordered – an observation that correlates with the large entropic penalty associated with inhibitor binding as revealed by ITC. NMR data, including 15N-1H residual dipolar coupling measurements, indicate that the sulfur atom in the inhibitor is important for stabilizing and restricting important motions of the L2 and L3 catalytic loops in the inhibited ternary complex. This work describes a comprehensive analysis of a new HPPK inhibitor, and may provide a foundation for the development of novel antimicrobials targeting the folate biosynthetic pathway.
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Affiliation(s)
- Sandeep Chhabra
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- CSIRO Division of Materials, Science and Engineering, Parkville, Australia
| | - Olan Dolezal
- CSIRO Division of Materials, Science and Engineering, Parkville, Australia
| | - Brett M. Collins
- Institute for Molecular Bioscience, The University of Queensland, Australia
| | - Janet Newman
- CSIRO Division of Materials, Science and Engineering, Parkville, Australia
| | - Jamie S. Simpson
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Ian G. Macreadie
- School of Applied Sciences, RMIT University, Bundoora, Australia
| | - Ross Fernley
- CSIRO Division of Materials, Science and Engineering, Parkville, Australia
| | - Thomas S. Peat
- CSIRO Division of Materials, Science and Engineering, Parkville, Australia
| | - James D. Swarbrick
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
- * E-mail:
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